A Conservative peer is to face a second parliamentary investigation into his lobbying activities on behalf of a Caribbean tax haven.

Lord Blencathra, formerly David Maclean, a Tory minister in John Major’s government, has previously been investigated by the Lords Commissioner for Standards for his work on behalf of the Cayman Islands government, following an investigation for The Independent by the Bureau of Investigative Journalism.

At the time he told the Commissioner, Paul Kernaghan, that he would never have agreed to lobby MPs and peers as part of his work.

But earlier this month, The Independent revealed that a contract, signed by the former Conservative Party Chief Whip, stated that the services he was to provide included: “making representations to … members of Parliament” in the Commons and Lords.

Lord Blencathra insisted that the lobbying clause was one of several which were never acted upon, that he had not carried out any lobbying on behalf of the Cayman Islands, and that what he told the commissioner was correct.

The investigation may focus on whether or not the peer broke conduct rules by signing the contract, even if there is no evidence that he lobbied.

The new investigation follows a complaint by the Labour MP Paul Flynn and Lord Blencathra referring himself to the Commissioner. In a letter to Mr Flynn, Mr Kernaghan wrote: “Lord Blencathra submitted a request that I investigate his behaviour on the basis of the article in The Independent. In accordance with the (Lords) code of conduct I have secured agreement of the sub-committee on Lords’ interest to investigate.

“His request and your complaint are identical in substance. My investigation is proceeding on [that] basis.”

Lord Blencathra has said he categorically denies any breaches of the House of Lords code of conduct and said he had not lobbied members of Parliament when carrying out any of his duties for the Cayman Islands government.

“I have referred myself to the Lords’ Commissioner for Standards so that he can investigate the allegations personally,” Lord Blencathra said in an email to the Caymanian Compass newspaper.

“I have refuted [the allegations] and I categorically deny that I am in breach of the code. [The Independent] has looked at the original contract which had included lobbying Parliament and has automatically assumed that I was in breach of the code, irrespective of whether or not I was lobbying,” Lord Blencathra added, stating that the sentence about lobbying MPs was removed from the agreement.

“The contract was then changed in December 2012 to remove all reference to MPs and Parliament – so that there could be no perception even that I was doing that. This is a rehash of the original allegation which was fully investigated and I was cleared.”

MPs and peers are prevented from using their positions to lobby the Government and fellow parliamentarians on behalf of paying clients.

The Independent reported in 2012 that Lord Blencathra’s work for the Cayman Islands government included lobbying and that he had written to the Chancellor, George Osborne, to complain about air passenger taxes on flights to the Caymans. Lord Blencathra told the Commissioner then that he did not lobby Parliament and would not do so. “None of my work involves lobbying Parliament or seeking to influence either House.”

The contract provided assurance to his Cayman bosses that there were no rules forbidding him from providing any of the services stipulated in the contract, which included lobbying MPs.